The increasing demand for higher data rates in wireless communications has led industry to develop innovative ways for transmitting data. Orthogonal Frequency Division Multiple Access (OFDMA) has been known to provide such increase and it is currently used in various standards. As of recent, discussions regarding the implementation of OFDMA into the IEEE802.11 High Efficiency WLAN (HEW) standard have occurred. OFDMA is considered a new technology in HEW. However, a challenge in using OFDMA is the concept of Resource Block (RB) allocation. Resource allocation varies widely as it is applicable to different operation bandwidths, different number of DC and pilot tones and different guard band configurations. For example, a 40 MHz channel may be used in downlink transmission to serve various users operating at 20 MHz and/or 40 MHz. When the access point (AP) sends data over to two 20 MHz subchannels for two users operating with 20 MHz bandwidth, three sets of DC tones are required. The first DC tone set is used by the AP and is located at the center of the 40 MHz, the other two sets of DC tones reside at the centers of the 20 MHz subchannels for the two receiving users. In contrast, when the entire 40 MHz is used to serve a single user operating at 40 MHz bandwidth, only one set of DC tones is needed. Therefor the number of DC tones varies with the serving users' operation bandwidths.
In building a RB, the total number of usable tones will vary based on the total allocated bandwidth by the system. Bandwidths currently vary between, for example from 20 MHz-160 MHz. Further, the number of DC tones and guard tones, link direction, and OFDM symbol duration will also impact total number of usable tones. As an example, a 20 MHz subchannel may need one, three, four, five or more DC tones, numerous guard tones and about 2 pilot tones per RB. Thus, making it impossible to utilize all the usable tones in all bandwidth, allocation, and link configurations without leftover tones. In some instances, as many as 12 leftover tones go unused. The leftover tones are a waste of usable bandwidth. It is with respect to these and other considerations that the present improvements have been developed.
The 802.11 standard specifies a common Medium Access Control (MAC) Layer which provides a variety of functions that support the operation of 802.11-based wireless LANs (WLANs). The MAC Layer manages and maintains communications between 802.11 stations (such as between radio network cards (NIC) in a PC or other wireless devises or stations (STA) and access points (APs)) by coordinating access to a shared radio channel and utilizing protocols that enhance communications over a wireless medium.
802.11n was introduced in 2009 and improved the maximum single-channel data rate from 54 Mbps of 802.11g to over 100 Mbps. 802.11n also introduced MIMO (multiple input/multiple output or spatial streaming), where, according to the standard, up to 4 separate physical transmit and receive antennas carry independent data that is aggregated in a modulation/demodulation process in the transceiver. (Also known as SU-MIMO (single-user multiple input/multiple output.))
The IEEE 802.11ac specification operates in the 5 GHz band and adds channel bandwidths of 80 MHz and 160 MHz with both contiguous and non-contiguous 160 MHz channels for flexible channel assignment. 802.11ac also adds higher order modulation in the form of 256 quadrature amplitude modulation (QAM), providing a 33-percent improvement in throughput over 802.11n technologies. A further doubling of the data rate in 802.11ac is achieved by increasing the maximum number of spatial streams to eight.
IEEE 802.11ac further supports multiple concurrent downlink transmissions (“multi-user multiple-input, multiple-output” (MU-MIMO)), which allows transmission to multiple spatial streams to multiple clients simultaneously. By using smart antenna technology, MU-MIMO enables more efficient spectrum use, higher system capacity and reduced latency by supporting up to four simultaneous user transmissions. This is particularly useful for devices with a limited number of antennas or antenna space, such as smartphones, tablets, small wireless devices, and the like. 802.11ac streamlines the existing transmit beamforming mechanisms which significantly improves coverage, reliability and data rate performance.
IEEE 802.11ax is the successor to 802.11ac and is proposed to increase the efficiency of WLAN networks, especially in high density areas like public hotspots and other dense traffic areas. 802.11ax will also use orthogonal frequency-division multiple access (OFDMA). Related to 802.11ax, the High Efficiency WLAN Study Group (HEW SG) within the IEEE 802.11 working group is considering improvements to spectrum efficiency to enhance system throughput/area in high density scenarios of APs (Access Points) and/or STAs (Stations).
In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the disclosed techniques. However, it will be understood by those skilled in the art that the present embodiments may be practiced without these specific details. In other instances, well-known methods, procedures, components and circuits have not been described in detail so as not to obscure the present disclosure.
Although embodiments are not limited in this regard, discussions utilizing terms such as, for example, “processing,” “computing,” “calculating,” “determining,” “establishing”, “analyzing”, “checking”, or the like, may refer to operation(s) and/or process(es) of a computer, a computing platform, a computing system, a communication system or subsystem, or other electronic computing device, that manipulate and/or transform data represented as physical (e.g., electronic) quantities within the computer's registers and/or memories into other data similarly represented as physical quantities within the computer's registers and/or memories or other information storage medium that may store instructions to perform operations and/or processes.
Although embodiments are not limited in this regard, the terms “plurality” and “a plurality” as used herein may include, for example, “multiple” or “two or more”. The terms “plurality” or “a plurality” may be used throughout the specification to describe two or more components, devices, elements, units, parameters, circuits, or the like. For example, “a plurality of stations” may include two or more stations.
Before undertaking the description of embodiments below, it may be advantageous to set forth definitions of certain words and phrases used throughout this document: the terms “include” and “comprise,” as well as derivatives thereof, mean inclusion without limitation; the term “or,” is inclusive, meaning and/or; the phrases “associated with” and “associated therewith,” as well as derivatives thereof, may mean to include, be included within, interconnect with, interconnected with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, or the like; and the term “controller” means any device, system or part thereof that controls at least one operation, such a device may be implemented in hardware, circuitry, firmware or software, or some combination of at least two of the same. It should be noted that the functionality associated with any particular controller may be centralized or distributed, whether locally or remotely. Definitions for certain words and phrases are provided throughout this document and those of ordinary skill in the art should understand that in many, if not most instances, such definitions apply to prior, as well as future uses of such defined words and phrases.